Hi, On 4/5/2016 10:11 AM, Rich Lane wrote: > For simple TX the virtio-net header must be zeroed, but it was using memory > that had been initialized with indirect descriptor tables. This resulted in > "unsupported gso type" errors from librte_vhost. > > We can use the same memory for every descriptor to save cachelines in the > vswitch.
Pointing all virtio_net_hdr into the same memory may brings performance, but how much? It also introduces difficulty to adding tso in future? Thanks, Jianfeng > > Fixes: 6dc5de3a (virtio: use indirect ring elements) > Signed-off-by: Rich Lane <rlane at bigswitch.com> > --- > v1-v2: > - Use offsetof to get address of tx_hdr > > drivers/net/virtio/virtio_rxtx.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/virtio/virtio_rxtx.c > b/drivers/net/virtio/virtio_rxtx.c > index 2b88efd..ef21d8e 100644 > --- a/drivers/net/virtio/virtio_rxtx.c > +++ b/drivers/net/virtio/virtio_rxtx.c > @@ -377,7 +377,7 @@ virtio_dev_vring_start(struct virtqueue *vq, int > queue_type) > vq->vq_ring.desc[i + mid_idx].next = i; > vq->vq_ring.desc[i + mid_idx].addr = > vq->virtio_net_hdr_mem + > - i * vq->hw->vtnet_hdr_size; > + offsetof(struct virtio_tx_region, > tx_hdr); > vq->vq_ring.desc[i + mid_idx].len = > vq->hw->vtnet_hdr_size; > vq->vq_ring.desc[i + mid_idx].flags =
